Changes needed for Assistant Chat

[mpivchev]

1. Currently the chat is not loading more messages after the first sent message. That is because we do not generate a session before polling. chat/new_message should always be followed by a chat/generate and then polling check_generation.

This is the full flow:

2. Add a "Retry response generation"

Upon running chat/check_session, If the last message is from a human and chatMessageTaskId is nil, we must add a button to retry the response generation:

• If chatMessageTaskId is NOT nil, then we rerun chat/check_generation with the chatMessageTaskId as a parameter.

3. When sending a message we must disable sending more messages while chat/check_generation is polling.
   Not sure if this already works on Android, but worth checking.

4. This should just say "Type a message..."

5. Selected conversation is not marked in Conversation list. Add a checkmark to indicate selected conversation.

6. Conversation title is not showed anywhere in the chat screen, so it's hard to keep track of the selected conversation. Title should be added.

7. Dates for each message should be formatted to mimic web and iOS.

8. (Optional) Since Assistant is now a button on front page on both iOS and Android, we can remove the icon here:

This is already removed on iOS.

[furai]

I don't use assistant, I don't have it installed on my server, yet it shows up in the nextcloud app and context menus when selecting text. This should be fixed as well.